#include <bits/stdc++.h>
using namespace std;

#define int int64_t
#define endl "\n"

using PII = pair<int, int>;
using TII = tuple<int, int, int>;
template<class T>
using V = vector<T>;
using i64 = long long;
using i128 = __int128;
using u64 = unsigned long long;

#define FOR(i, a, b) for (int i = (int)(a); i <= (int)(b); i++)
#define FOR2(i, a, b, c) for (int i = (int)(a); i <= (int)(b); i += c)
#define FORD(i, b, a) for (int i = (int)(a); i >= (int)(b); i--)
#define FORD2(i, b, a, c) for (int i = (int)(a); i >= (int)(b); i -= c)
#define ALL(a) a.begin(), a.end()
#define RALL(a) a.rbegin(), a.rend()
#define lowbit(x) ((x)&(-x))
#define RE return;
#define Yes cout << "Yes" << endl;
#define YES cout << "YES" << endl;
#define No cout << "No" << endl;
#define NO cout << "NO" << endl;
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define sz size()

void solve () {
    int n, m;
    cin >> n >> m;

    V<V<PII>>g (n + 1);

    FOR (i, 1, m) {
        int a, b, c;
        cin >> a >> b >> c;
        g[a].eb (b, c);
    }

    V<V<int>>vis (n + 1, V<int> (1048, 0));
    queue<PII>q;

    q.push ({ 1,0 });

    while (q.sz) {
        auto [ver, v] = q.front ();
        q.pop ();

        for (auto [j, w] : g[ver]) {
            int t = v ^ w;
            if (vis[j][t])continue;
            vis[j][t] = 1;
            q.push ({ j,t });
        }
    }

    FOR (i, 0, 1024) {
        if (vis[n][i]) {
            cout << i;
            RE;
        }
    }
    cout << -1;
}

signed main () {
    int Task = 1;

    ios::sync_with_stdio (false);
    cin.tie (nullptr);

    while (Task--) {
        solve ();
    }

    return 0;
}